Polymetal Mine (Ruby Tuesday; Research; Chomly; Ketchikan Copper Company prospects), South Arm of Cholmondeley Sound, Cholmondeley Sound, Prince of Wales Island, Ketchikan District, Prince of Wales-Outer Ketchikan Borough, Alaska, USA

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Location: This property was staked prior to 1902 by the Ketchikan Copper Company and it is so named in several old reports. A 297-foot adit was driven under the mineralization and the ARDF site is at that adit. The adit is at an elevation of about 1,300 feet, about 2.5 miles SW of the mouth of the South Arm of Cholmondeley Sound, and near the SW corner of section 4, T77S, R87E. After WW II, the property was restaked several times by several parties, and there was considerable exploration in the 1980's and early 1990's, when the property consisted of more than 70 claims. Most of the work was in an area about 1,800 feet in diameter centered near the location of the original claims.

Geology: This property was staked before 1902 (Brooks, 1902) by the Ketchikan Copper Company and it is so named in the early reports. A tunnel was driven for about 300 feet to intersect the ore body at depth, but apparently stopped short of it. The deposit was restaked as the Polymetal Lode in 1948 and was explored by one or more shallow drillholes in the mid-50's (Maas and others, 1991, 1995). It was restaked in 1973 and drilled by ASARCO under lease. Noranda restaked a large area around it in 1978 and 1979 as the Ruby Tuesday claim block. LAC Minerals (USA) Incorporated gained a controlling interest in the property in 1988 and brought in Kennecott Exploration as a partner in 1993. There were at least 11 holes totaling more than 7,300 feet drilled on the property through early 1993 (LAC Minerals (USA) Incorporated, 1989). There has been no production and no reserve figures have been published. The rocks in the area consist of intricately folded and faulted, greenschist-grade, chlorite schist, sericite schist, marble, siliceous and graphitic pelitic rocks, felsic tuff, and undivided pelitic and volcaniclastic rocks (Herreid and others, 1978; Kucinski, 1987; Maas and others, 1991, 1995). The rocks are part of the Wales Group of Late Proterozoic and Cambrian age. The main deposit, the Polymetal, is a stratiform volcanogenic massive-sulfide deposit that consists of thin stringers and layers of sphalerite, pyrite, galena, and chalcopyrite in siliceous felsic tuff near its contact with black argillaceous chert. Recent detailed geochemical and isotopic work by Slack and others (2002) confirm that the deposit is of Late Proterozoic or Cambrian age. Fowler (1949) sampled the outcrop of a 20-foot-thick mineralized zone; it averages 11.1 percent zinc, 3.1 percent lead, and a trace of silver. The nearby Chomly deposit is in a different stratigraphic horizon; it consists of patches of sphalerite and galena up to 4 inches thick and 3 feet long in black argillaceous chert.

Workings: This property was staked before 1902 (Brooks, 1902) by the Ketchikan Copper Company and it is so named in the early reports. A tunnel was driven for about 300 feet to intersect the ore body at depth but apparently stopped short of it. The deposit was restaked as the Polymetal Lode in 1948 and was explored by one or more shallow drillholes in the mid-50's (Maas and others, 1991, 1995). It was restaked in 1973 and drilled by ASARCO under lease. Noranda restaked a large area around it in 1978 and 1979 as the Ruby Tuesday claim block. LAC Minerals (USA) Incorporated gained a controlling interest in the property in 1988 and brought in Kennecott Exploration as a partner in 1993. There were at least 11 holes totaling more than 7,300 feet drilled on the property through early 1993 (LAC Minerals (USA) Incorporated, 1989).

Age: Contemporaneous with the deposition the Late Proterozoic or Cambrian host rocks.

Alteration: Intense alteration was noted in one report but was not described specifically. The mineralized zone is oxidized and iron stained at the surface.

Commodities (Major) - Ag, Cu, Pb, Zn

Development Status: None

Deposit Model: Volcanogenic Cu-Pb-Zn massive sulfide deposit (Cox and Singer, 1986; model 28a)

Mineral List

Chalcopyrite Galena

Pyrite Quartz

Sphalerite

5 entries listed. 5 valid minerals.

References